NASA's DC-8 flying laboratory takes off from its base at the Dryden Aircraft Operations Facility in Palmdale for the IceBridge Mission. The flights for the mission are based in Punta Arenas, Chile. (NASA Photo by Tony Landis)› View Larger Image Scientists returned in late October to the Southern Hemisphere, where NASA's Operation IceBridge mission is set to begin a second year of airborne surveys over Antarctica. The mission monitors the region's changing sea ice, ice sheets and glaciers.

Researchers are flying from Punta Arenas, Chile, on NASA's DC-8, a 157-foot-long airborne laboratory equipped with a suite of seven environmental instruments. The focus is to re-survey areas undergoing rapid change and to embark on new lines of investigation. Based at the Dryden Aircraft Operations Facility in Palmdale, Calif., the DC-8 flying lab and its flight crew and scientists flew from Palmdale to Punta Arenas.

"We are excited to learn how the glaciers and sea ice have changed since last year's campaign," said Michael Studinger, IceBridge project scientist at Goddard Space Flight Center in Greenbelt, Md.

"We also are going to be mapping uncharted regions that will allow us to better assess future behavior of the Antarctic ice sheets and sea ice."

IceBridge science flights will continue through mid-November. Flights depart Punta Arenas and cross the Southern Ocean to reach destinations including West Antarctica, the Antarctic Peninsula and coastal areas. Each flight lasts about 11 hours.

Instruments for the 2010 Antarctic campaign are the same as those flown in 2009. A laser instrument maps and identifies surface changes. Radar instruments penetrate snow and ice to provide views of what lies beneath for use in developing a profile of the ice's characteristics and also of the shape of the bedrock supporting it. A gravity instrument measures the shape of seawater-filled cavities at the edge of some major fast-moving glaciers.

Using these tools, researchers are surveying targets of ongoing and potential rapid change, including the West Antarctic Ice Sheet, which is the area with the greatest potential for triggering a rapid increase in sea level. Another concern stems from the fact that the ice sheet is below sea level, which adds to its instability.

Revisiting previously flown areas, scientists can begin to quantify the magnitude of changes to land ice. Pine Island Glacier, the largest ice stream in West Antarctica and one with significant potential for contributing to sea level rise, has long been a primary target for sustained observation.

Satellite data, most recently from NASA's Ice, Cloud and land Elevation Satellite, or ICESat, have shown dramatic thinning there of up to 10 meters per year in places. Previous IceBridge flights mapped the surface of the glacier and unusual features beneath it, providing clues to the glacier's rapid retreat and ice loss.

In addition to flying previous routes over the glacier, the IceBridge team plans to fly a new horseshoe pattern to sample tributaries feeding into Pine Island Glacier's main trunk. Other new flight lines will further explore the Antarctic Peninsula for purposes of mapping new targets, including the George VI Ice Shelf, above and below the ice.

Three high-priority flights are aimed at measuring sea ice. One goal involves mapping and measuring sea ice across the Weddell Sea. Scientists want to know why sea ice in Antarctica is growing in extent, unlike sea ice in the Arctic, which is declining in extent. Current theories range from ozone depletion to changing ocean dynamics.

Other flights are planned in coordination with existing space and ground-based missions, such as one involving the European Space Agency's ice-observing Cryosat-2 satellite and another in connection with European ship-based research. Overlapping measurements help researchers calibrate instruments and boost confidence in resulting observations.

"A concerted effort like this will allow us to produce long time series of data spanning from past satellite missions to current and future missions," Studinger said. "This is only possible through international collaboration.

"We are excited to have so many opportunities to work with our international partners during the upcoming campaign."